Relay



Feb. 20, 1962 w. R. BAUER RELAY Filed Sept. 4. 1959 3,022,399 PatentedFeb. 20, 1962 3,022,399 RELAY Werner R. Bauer, Columbus, Ohio, assignorto RobertshaW-Fulton Controls Company, Richmond, Va., a corporation ofDelaware Filed Sept. 4, 1959, Ser. No. 838,262 7 Claims. (Cl. 200-87)This invention relates to electromagnetic relays.

An electromagnetic relay is customarily comprised of a switch meanswhich is movable between controlling positions in response toenergization and deenergization of an electromagnet or solenoid. Theelectromagnet attracts an armature to cause movement of the switchmeans. To increase the attractive force acting upon the armature withoutincrease in the energizing current, or to decrease the energizingcurrent and hold the attractive force constant, it is desirable toreduce the resistance of the magnetic circuit in its most effectiveportion, e.g., the air gap. One method of accomplishing this would be tomove the armaturecloser to the core of the coil assembly; however, thisis not desirable in many instances since it might also reduce the amountof armature travel below that amount necessary to actuate the switchmeans. Accordingly, it is an object of this invention to reduce themagnetic resistance by reducing the air gap without adversely aifectingmechanical movement of the armature.

Another object of this invention is to allow the attractive force toremain the same and yet reduce the energizing current.

Another object of this invention is to develop a better contact pressureby reducing the possibility of oscillations, which would normally bedeveloped when using a coil spring for biasing the armature.

A further object of this invention is to allow the contact pressure tobe adjusted so that the armature is balanced.

Still another object of this invention is to prevent side loading of thearmature and biasing means from affecting the operation.

Other objects and advantages of this invention will be apparent from thefollowing description taken in connection with the accompanying drawingwherein:

FIG. 1 is a front elevational view, with portions removed, of anembodiment of this invention;

FIG. 2 is an end elevational View of the device shown in FIG. 1;

FIG. 3 is a bottom plan view of the device shown in FIG. 1;

FIG. 4 is a bottom plan view of a detail;

FIG. 5 is a perspective view, on an enlarged scale, of another detail;

FIG. 6 is a bottom plan view, of still another detail; and

FIGS. 7 and 8 are somewhat schematic views of a portion of the device. 7

Referring now to the drawing and more particularly to FIGS. 1 3, arelay, indicated generally by reference numeral 28, generally comprisesa stacked switch assembly 22 operatively connected to be actuated by anelectromagnet or solenoid 24 embodying an armature 26 and a spring 28.Switch assembly 22 may include switch means of many forms. By way ofexample only and for the purposes of illustration, the switch means maytake the form of one which operates on the principle of the snapactingdevice disclosed in US. Patent 2,558,258, Kohl, to which reference maybe made for a more detailed description of the theory and principle ofoperation. As shown, switch assembly 22 includes an adjacent pair ofsuch switch means, 30, 30 disposed on both sides of on an enlargedscale,

switch assembly 22. Each switch means 30 is a single pole, double throw,snap-acting switch which is movable between controlling positions inresponse to movement of an actuating lever 32.

Coil assembly 24 is shown, by way of example only and for the purposesof illustration, in the form adapted to be energized by an alternatingcurrent. Coil assembly 24 comprises a coil 34 wound upon a plasticbobbin 36 into which a core 38 (FIGS. 7 and 8) is inserted. Core 38 isformed at its upper end into a pair of D- shaped pole pieces 40. Asillustrated by the dotted lines in FIG. 6, pole pieces 40 are separatedslightly and are disposed in a back-to-back relationship. A shading coil42 is provided with a pair of D-shaped apertures (not shown). Duringassembly, pole pieces 48 are inserted into these apertures and thecorner portions of pole pieces 40 are upset to aflix coil 42 to core 38.The wire ends 44, 44 of coil 34 are staked to terminals 46, 46 mountedupon a portion of bobbin 36.

Coil assembly 24 is attached to leg 48 of a metallic, U-shaped, magneticframe 50, comprising a medial section 52 and an upper leg 54, by a screw56 which extends through an aperture formed in leg 48 and which isscrewed into a threaded aperture formed in the bottom end of core 38. Abrass washer 58 is disposed between leg 48 and core 38 to reduceresidual magnetism.

Leg 54 intersects medial portion 52 at substantially a right angle. Atthis intersection, portion 52 is formed with a widened T-shaped aperture60 which extends across a substantial portion of the width of portion52. Armature 26 is disposed within this aperture so that the reducedwall portion of the T-shaped aperture fits into a pair of slots 62, 62formed on the sides of armature 26 adjacent to the reduced width end 64,to prevent longitudinal movement of armature 26, yet permit armature 26to pivot about frame 50.

Switch assembly 22 includes a base plate 66 which is mounted upon frame50 by a screw 68 which extends through an aperture 70 formed in baseplate 66 and through an aperture 72 formed in spring 28 and which isscrewed into a threaded aperture formed in leg 54. Spring 28 is thussandwiched between plate 66 and leg 54 and is formed with an aperture 74so as to define a tab 76 and a U-shaped cantilever leaf spring having atip 78 connected by side legs 80, 80 to the main body portion.

As best seen in FIG. 5, tab 76 is bent at a right angle and extendsdownwardly towards armature 26 but terminates short thereof to providemeans for preventing armaature 26 from being separated from frame 50.Legs 80, 80 are also bent downwardly at right angles so that tip 78engages end 64 to bias armature 26 counterclockwise, as viewed in FIG.1, against stop means in the form of a tab 82 formed from leg 54. Baseplate 66 is formed with side slots 84, 84 which overlie legs 80, 80 toallow these legs to move upwardly upon clockwise movement of armature 26from the position shown in FIGS. 1 and 8.

The width of tip 78 is greater than that of end 64, as best seen in FIG.3, to provide substantially a line contact whereby there will be an evenapplication of armature 26 on frame 50, even with side loading thereon.Spring 28 is thin and provides a short moment arm having a relativelysmall unsupported mass so that oscillation is held below that whichwould occur if a coil spring were used. To allow adjustment of thiscontact pressure, spring 28 is formed with a pair of slots 86, 86 intowhich a pair of lugs 88, 88 formed on the underside of plate 66, extend.By loosening screw 68, spring 28 can he slid within limits to thedesired position.

Armature 26, as best seen in FIGS. 6-8, is formed with air gap reducingmeans in the form of an arcuate, preferably serni-circular, projectionor ridge 90 which extends downwardly from the underside of armature 26towards pole piece 4 As shown in FIG. 8, armature 26 is in theunattracted position. Dimension a represents the air gap in the magneticcircuit. Ridge 9t is movable in an arcuate path but does not engage polepiece it) to interfere with or hinder movement of armature 26. Whenarmature 26 is horizontal, an upward projection of pole piece 4d wouldintersect the armature substantially as shown by the dotted lines inFIG. 6.

In one embodiment, and by way of illustration only, the air gap is.023", as opposed to an air gap of .036 for similar armatures notprovided with ridges. Ridge 90 is formed in a die so that, although itdistorts the grain somewhat, it does not destroy the grain so as tochange the magnetic flow. In the attracted position shown in PEG. 7, thelower portion of ridge $0 is below the level of the upper surface ofpole piece it? so as to partially encompass the same.

Armature 26 is provided with a pair of tabs 92, @2 which are insertedthrough apertures formed in a connector 94 and which are upset to aflixconnector 9 to armature 26 for movement therewith. Connector 94 isconstructed from relatively rigid insulation material and is also formedwith a slot 96 (FIG. 2) into which the ends of actuating levers 32 areinserted.

In operation, the terminals of relay 2% are connected to the circuits tobe controlled. When coil assembly '24 is deenergized, armature 28 isbiased counterclockwise by spring 28, as shown in FIG. 1, against tab82.

Subsequent energization of coil assembly 24 causes armature 26 to pivotclockwise until, as shown in FIG. 7, the underside of armature 25engages the right hand portion of pole piece 4b. This movement causesend 64 to move tip 73 so that legs 39, 80 move upwardly into slots 84,84. This movement also causes connector 94% to move actuating lever 32,downwardly to cause switch means 35) to snap between positions. Whencoil assembly 24 is subsequently deenergized, spring 28 moves armature26 and connector 94- so that switch means 30 snaps to its normalposition.

It will be apparent that many changes may be made in the details ofconstruction and arrangement of parts without departing from the scopeof the invention as defined in the appended claims.

I claim:

1. A relay comprising: a U-shaped frame; a coil assembly mounted on oneof the legs of said frame and extending towards the other leg butterminating short thereof; an armature pivoted on a portion of themedial section of said frame and extending between said coil assemblyand said other leg, said armature being formed with air gap reducingmeans; a switch assembly including a base plate mounted on said otherleg, said switch assembly further including switch means operativelyconnected to said armature; and spring means sandwiched between saidother leg and said base plate and including a portion which abuts saidarmature to bias the same to a controlling position.

2. A relay comprising: a frame including first and second portionsjoined together to form a right angle, said portions being formed withan aperture; an armature having an end portion which extends throughsaid aperture and being cooperable with said first portion to allow saidarmature to pivot and to restrain said armature from longitudinalmovement; a base plate mounted on said second portion; a leaf springmounted between said base plate and said second portion and beingoperatively connected to bias said armature in one direction, saidspring including a tab which extends through said aperture and preventssaid armature from being separated from said frame.

3. The device of claim 2 wherein said base plate is formed with a pairof lugs and said spring is formed with a cooperating pair of aperturesinto which said lugs extend, said apertures being substantially largerthan said lugs to allow said spring to be moved.

4. A relay comprising: a U-shaped frame; a coil assembly mounted on oneof the legs of said frame and extending towards the other leg butterminating short thereof; an armature pivoted on a portion of themedial section of said frame and extending between said coil assemblyand said other leg, said armature being formed with a semi-circularridge which cooperates with said coil assembly to reduce the air gap andmagnetic resistance; a switch assembly including a base plate mounted onsaid other leg, said switch assembly further including switch meansoperatively connected to said armature; and spring means operativelyconnected between said switch assembly and said frame and beingconstructed from relatively thin, fiat spring material, said springmeans being formed with a main body portion, a tab extending away fromsaid main body portion and being adapted to prevent said armature frombeing removed from said frame, said spring means being formed withapertures therein for adjusting the position of said spring means, andsaid spring means having two narrow legs extending from said main bodyportion with each leg bent toward said armature at a point removed fromsaid main body portion, a third leg joining the ends of said narrow legsremoved from said main body with an edge of said third le engaging saidarmature for biasing said armature toward a controlling position.

5. A relay comprising a coil, a core, a pole piece assembly on said coreprojecting axially from one end of said coil, an armature overlying saidone end of said coil, means supporting said armature for pivotalmovement toward and away from said one end of said coil between anunactuated position spaced from said pole piece assembly and an actuatedposition in contact with said pole piece assembly, switch meansoperatively coupled to said armature for actuation by said armature, andan air gap reducing ridge projecting from said armature toward said oneend of said coil at a location such that said ridge partiallyencompasses said pole piece as sembly in spaced relationship therewithwhen said armature is in said actuated position, said ridge defining thepath of least magnetic resistance between said pole piece assembly andsaid armature when said armature is in said unactuated position.

6. A relay as defined in claim 5 wherein said means supporting saidarmature for pivotal movement comprises a frame, and means on said framecooperable with means on said armature to support said armature forpivotal movement about an axis normal to the axis of said coil at alocation spaced from one side of said coil at said one end thereof, saidair gap reducing ridge being located between said axis and said polepiece assembly when said armature is in said actuated position.

7. In a relay having a frame, and a relay coil mounted on said frame; arelay armature having a. fiat portion at one end thereof, cooperatingmeans on said frame and said armature supporting said armature forpivotal movemert toward and away from one end of said coil about an axisextending transversely of said armature and parallel to the generalplane of said fiat portion at a location spaced inwardly of saidarmature from said one end thereof, a leaf spring member having a fixedend and a free end, said free end of said spring member terminating in astraight edge having a length at least equal to the transverse width ofsaid fiat portion of said armature, and means mounting said fixed end ofsaid spring member upon said frame to locate said straight edge of saidspring member in contact with said fiat portion of said armature along aline extending transversely across said armature in parallelrelationship to said axis at a location between said axis and said oneend of said armature, the portion of said leaf spring memberintermediate said fixed end and said free end being constructed and ar-References Cited in the file of this patent UNITED STATES PATENTS HedmanSept. 15, 1903 6 Henderson June 11, 1918 Rahling Nov. 18, 1919 Bogue eta1. Feb. 21, 1956 Scale Dec. 8, 1959 Wallace et a1 Mar. 15, 1960

